Interlocking system for railroads



es. 9, 1941. F. B. HITCHCOCK 2,255,231

INTERLOCKING SYSTEM FOR RAILROADS Filed April 16, 1936 2 Sheets-Sheet l fl ATTORNEY Dec. 9 1941; F. B. HITCHCOCK INTERLOCKING SYSTEM FOR RAILROADS Filed April 16, 1936 2 Sheets- Sheet 2 INVENTOR ATTORNEY Patented Dec. 9, 1941 INTERLOCKING, SYSTEM FOR RAILROADS Forest B. Hitchcock, Greece, N. Y., assignor to General Railway Signal Company, Rochester,

Application April 16, 1936, Serial No. 74,'l09

31 Claims.

This invention relates to centralized tratfic controlling systems for railroads, and more particularly pertains to the indication of route conditions to the operator in a central oilice.

The present invention relates to improvements in the indications provided in a system of the so called entrance-exit route type interlocking system disclosed in the prior application of S. N. Wight, Ser. No. 69,905, filed March 20, 1936.

The organization of a system embodying the present invention contemplates a miniature track diagram located in the central office which corre sponds to the actual track layout in the field, and has located thereon initiating or entrance buttons at each of the route determining points on the track layout, and completion or exit buttons for each of the points to which trafiic may go. In other words, for each signal location there is an entrance button, which button requires the cooperation of an exit button for the end ofsuch proposed route in order to establish movement of traflic in a particular direction over a particular trackway route.

In accordance with the present invention, the entrance and exit buttons are located on the miniature track diagram which has a grooved channel in a dark colored panel to represent the trackway. At the base of the groove, a distinctive colored strip, such as white for example, of Celluloid or equivalent material is used to render this groove readily visible. Between the entrance and exit buttons for the various routes are located openings in the base of such grooves representing the trackway. These openings are beneath the colored strip and are provided with indicator lamps which are at times illuminated, and the illumination of which indicates to the operator the condition of the trackway route and the position of the track switches in such route.

In other words, the present invention proposes to provide an illuminated track diagram whichgives the desired route information, including the position of the track switches, in such a manner as to advise the operator of composite route conditions. Such indications may be termed integrated indications, and as such they are particularly useful with the integrated type of control provided in an entrance-exit type of control system.

Other objects, purposes and characteristic feat tures of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference will be made to the accompanying drawings, in which like reference characters designate the same parts throughout the several views; and in which like letters in the reference characters designate similar functions or relationships with the distinctiveness between such reference characters provided by the use of distinctive preceding numerals; in which like preceding numerals in the reference characters, when applied to dif- :ferent letters, represent the inclusion of such device within a particular group; and in which- Fig. 1 illustrates a control panel as constructed in accordance with the present invention and illustrating the appearance under normal conditions when there is no traflic;

Fig. 2 is the same as Fig. 1, but shows the appearance of the panel upon the establishment of a particular route over the chosen trackway layout;

Fig. 3 shows a detail sectional view of a route indicator lamp located in the back of the panel and taken on lines 33 of Fig. 2;

Fig. 4 shows'a section of the control panel with all of the distinctive colored strips removed so as to show recesses in back of which the illumina-ting indicators are located; and

Fig. 5 shows the detail circuit control of the indicators provided in accordance with the present invention.

For the purpose of further simplifying the illustration and facilitating in the explanation thereof, various parts and circuits constituting the embodiment of the invention have been shown diagrammatically, and certain conventional illus-' gtrations' have been employed, the drawings hav- U of electric current supply instead of showing all of the Wiring connections to such terminals.

Symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of electric energy; and those terminals with which these symbols are used are presumed to have current flowing from the positive terminal designated to the negative terminal designated Symbols employed with any one circuit are considered to designate a single source of energy in this embodiment of the present invention but Apparatus in general Track layout, Fig. 5.In the accompanying drawings, the invention has been shown applied to a track layout including a stretch of double track connected by a crossover having switches TSa and T81), which crossover will be hereinafter referred to as crossover TS inasmuch as the opposite ends of such a crossover are usually operated at the same time. For convenience, the crossover TS has been indicated as operated by a single switch machine ISM, although two such machines may be used, and these machines may be of any suitable type, such for example, as disclosed in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923. However, it should be understood that the invention is not limited, as thus shown. to the control of a crossover, but may be applied to any track layout found in practice.

The track layout includes a main line track having rails 6 which are divided into a track circuit by the usual insulated joints including the usual track battery and a track relay 6T. Similarly, the other main line track includes the track rails I which are divided into a track circuit by the usual insulated joints having the usual track battery and track relay IT. The crossover is of course connected to the main track by suitable bonds (not shown) so as to be partly included in the track circuit for the rails 6 and partly in the track circuit for the rails 1 in such a manner that one or the other or both of the track relays will be deenergized when a car or train is on the crossover.

Signal 2 provides for governing east bound trailic over the rails I while signal 3 provides for governing west bound traffic over the rail-s I as well as over the crossover. Similarly, signal 4 provides for governing east bound traffic over the rails 6 and over the crossover, while signal providesv for governing west bound traffic over the rails 6. Although the signals 3 and 4 are shown as governing both main line and turn-out trafiic, it is to be understood that separate signals maybe employed if desired.

The crossover TS and switch machine ISM preferabl has associated therewith a point detector. contact mechanism, as shown for example in the patent to C. S. Bushnell, No. 1,517,236, dated November 25, 1924. The contacts of this mechanism (not shown) are provided to control a switch position indicating relay WP of the usual polar neutral type over the usual polarized circuit, so that the relay W? is energized with one polarity or the other when the track switch is in normal or reverse locked positions respectively in correspondence with the switch machine ISM, and is deenergized whenever the crossover is unlocked or is operated either by the switch machine ISM or by hand.

Control panel, Fig. 1.-In the central ofiice, a control machine has located. thereon a control panel preferably of dark colored Bakelite, or other material, upon which is formed by suitable grooves a track layout which corresponds to the actual track layout in the field. At the base of these grooves are suitable translucent strips which are of a distinctive color such as white so as to make the track layout stand out on a dark background. Located on this control panel are suitable control buttons and indicators including the entrance buttons ZNB, 3NB, GNB and 5N3,

which buttons are in positions corresponding to their respective signals as indicated by the preceding numerals. Located at the center of these buttons are suitable indicators ZSK, 35K, 4SK and 5SK which have arrows located on their lens for indicating the direction which the corresponding signal governs. These indicators are illuminated when their corresponding signals are cleared in a manner which has been specifically shown in the above mentioned prior application of S. N. Wight, Ser. No. 69,905, filed March 20, 1936.

The rotation of an entrance button NB in the direction of traffic, or as otherwise determined, causes the energization of its respective repeating relay R of which the relays 2R, 3R, 4B and ER are shown in Fig. 5, which detail control is shown specifically in the above mentioned application of S. N. Wight, Ser. No. 69,905, filed March 20, 1936. The details of this control are omitted for the sake of simplicity, it being suflicient for an understanding of the present invention to know that when an entrance button is rotated that its corresponding repeating relay is picked Similarly, the exit buttons XB are of the selfrestoring push button type and have arrows located thereon which indicate the direction of trafiic which they govern. The actuation of an exit button XB closes contacts for the control of route relays as shown specifically in Fig. 5.

In Fig. 4 of the accompanying drawings, a section of the panel including that part of the track layout corresponding to the crossover has been shown with all buttons and indicators removed to illustrate the recesses or slots in the panel beneath which the route indicating lamps are located and over which the translucent strips are positioned. With reference to Fig. 4, a slot is shown as extending from end wall I5 to end wall I6 beneath which slot the route indicator lamp 4--5L is located. Similarly, a slot from end wall I I to end wall IB is provided beneath which the route indicator lamp 2'-3L is located.

Two slots, one from end wall I9 to end wall 29 and the other from end wall Z'I to end wall 22 are provided for the crossover, and the route lamp 4--3L is located beneath both of these slots.

It is thus seen that the slots in the panel through which the light from the indicators may pass, are so located as to provide supporting projections between the various sections of the panel. Not only does the cross member between the end walls 20 and 2| in the panel provide a support, but it also provides a dark spot in the illuminated trackway representative of the division of the track-way into track circuits, that is, represents the insulated joints between such circuits.

In Fig. 3, the indicator lamp 4-3L has been shown with a section of the panel I4 taken on lines- 3-3 of Fig. 2. The trackway groove for the crossover has the translucent strip 23. The cross member having end walls 20 and 2! is clearly seen in the trackway representative of the insulated joint and providing suitable support between the;

sections of the panel. The lamp 4-,-3L is suitably supported beneath the-crossover slots on a support member 24 suitably attached to the-panel 14. This lamp 4-3L is alsoprovid-ed with a cover 25 which encloses the lamp so as to confine the;

light, when it is illuminated, to its own slots:in the panel. This cover 25 is suitably mounted on the support member 24 so as to be readily removable in the event that the lamp 43L burns out and needs to be replaced.

A similar arrangement is provided for each lamp 4-5L and 2-3L beneath their respective slots in the track diagram.

Above the portion of the miniature track diagram representative of the crossover 'TS, is located a switch control lever ISML and also a correspondence lamp or indicator ICOR. This switch control lever and its correspondence indicator are used more particularly under emergency conditions, and may be located in back of the panel if so desired.

The condition of track occupancy is indicated on the control panel by the indicators BTK and 'FTK which are suitably controlled by their corresponding track relays ST and IT, all of which has been omitted from the present disclosure for the sake of simplicity.

Control circuits, Fig. 5.-Associated with the entrance andexit buttons NB and XB respectively, are suitable route relays of the polar neutral type shown as relays 4-5, 4-3 and 23. These route relays are controlled in a manner more specifically pointed out hereinafter, and also described in detail in the above mentioned application of S. N. Wight, Ser. No. 69,905, filed March 20, 1936, and effect the control of the crossover through a switch control relay Z of the polar neutral type, which is'located in the central office together with a lock repeating relay LP of the neutral slow rel-easing type.

The control of the track switch is transmitted to the field over a line wire 26 and a common return wire 21 to which the relay WZ is responsive for locally controlling the switch machine ISM. A look relay L in the field is controlled through a signals-at-stop relay M and the track relays GT and IT as Well as suitable approach locking AP which has merely been indicatedv as a jumper, it being understood that the usual expedients provided in accordance with approach and release locking may be inserted without departing from the scope of the present invention.

Although the switch position repeating relay WP is usually located in a field and a repeater provided in a central office, for the sake of simplicity only the relay WP has been shown as located in the central office inasmuch as suitable control may be provided to accomplish this in an obvious manner.

A flashing relay F (or other suitable means) is provided to intermittently apply through back contact 52 to the bus wire whenever a relay Z is picked up, or continuously if such operation appears expedient.

An emergency push button lEB is provided in the central office for the purpose of obtaining an indication of the position of the switch when a route is not set up nor initiated, but it is to be understood that this push button IEB may be omitted if desired.

It is believed that the characteristic features of the present invention will be best understood by further description being given from the standpoint of operation.

Operation Setting. up a route.-Let us assume that the operator desires to setup a route over the crossover TS from signal 4 to the signal 3 and on through the interlocking plant. To do this, he rotates the entrance button 4NB (see Fig. 1) in a clockwise direction until the pointer on such button agrees with the position of the arrow on the signal indicator 45K. Then knowing that there is no route set up over the crossover because its route indicators are unilluminated, he actuates the eXit button 3X5.

As previously mentioned, the actuation of the entrance button 4NB energizes or picks up the relay 4R. (see Fig. 5). Thus, a circuit is closed for the route relay 43 from through a circuit including front contact 30 of relay 4R, back contact 3| of route relay 45, windings of route relay 4--3, back contact 32 of route relay 2-3, back contact 33 of relay 3R, back contact 34 of exit button 3XB, to The current which flows in this circuit actuates the polar contacts of the route relay 4--3 to the right and picks up its neutral contacts so that a stick circuit is closed including front contact 35 of route relay 4-3 and polar contact 36 of route relay 4'3 in a right hand position to shunt out the contact 34 of the exit button 3XB which contact is only momentarily closed as it is a self-restoring push button contact.

The picking up of the contacts of the route relay 4-3 opens the pick up circuit for the route relay 4-45 at back contact 3'! and similarly opens the pick up circuit for the route relay 23 at back contact 38. Therefore, it is obvious that no other route, can be initiated.

The picking up of route relay 43 closes an energizing circuit for the switch controlling relay Z from through a circuit including front contact 40 of relay'43, lower reverse winding of relay Z, back contact 4| of relay Z, to The current which flows, in this circuit causes the polar contacts of the relay Z to be actuated to. left hand positions and its neutral contacts to pick up, but inasmuch as the polar contacts of such a relay respond before its neutral contacts, the polar contact 42 assumes a left hand position to apply to the right hand terminal of the lower winding prior to the opening of back contact 4| of relay Z.

The opening of the back neutral contacts of the relay Z prevents further operation of such relay either by the route relays or by the emergency switch control lever lSML. More specifically, the closure of front contact 43 of route relay 2-8, or the actuation of the emergency switch control lever ISNL to the right to close contact i l in a left hand position, applies energy from to the left hand terminal of the upper Winding of relay Z, but this proves ineffective to energize the relay Z because the polar contact 42 of relay Z is in a left hand position and because the back contact 45 of relay Z is open.

The actuation of the polar contacts of the relay Z to left hand positions causes energy to be applied by polar contact 46 from the negative terminal of battery B through the upper winding of relay LP, front contact 41 of relay LP, polar con tact 48 of relay WP in a right hand position, line wire 26, front contact 49 of relay L, windings of relay WZ, over the common return line 2'! to the midtap of the battery B. The energy which flows in this circuit causes the polar contacts of the relas WZ to be actuated to left hand positions in which energy is applied from through front contact 59 of relay WZ, and polar contact 5| of relay WZ in a left hand position to the reverse operating circuit for the switch machine ISM. This application of energy to the switch machine ISM causes the crossover TS to be operated to a reverse locked position.

Immediately upon the actuation of the route relay 4-3 followed by the energization of the switch controlling relay Z, a circuit is closed for the route lamp 4-3L from through a circuit including back contact 52 of relay F, bus wire 15,

. front contact 53 of relay LP, front contact 54 of relay Z, polar contact 55 of relay Z in a left hand position, through the lamp 43L, to The current which flows in this circuit is intermittently interrupted by the flashing relay F at back contact 52. The flashing or intermittent illumination of this indicator 4-3L displays an indication to the operator (as indicated by shading of the trackway in Fig. 2) that the actuation of the completion button has accomplished the initiation of the route he intended.

The operation of the crossover TS to a reverse position causes the operation of the polar contacts of the relay WP to left hand positions followed by the picking up of its neutral contacts. When such operation has been completed, a circuit is closed for clearing the signal 4 from through a circuit including front contact 53 of relay WP, polar contacts 51 of relay WP in a left hand position, front contact 58 of route relay 43, polar contact 59 of relay 43 in a right hand position, wire 60, through the various selections necessary to clear the signal 4 which has merely been indicated by a dotted line.

The clearing of the signal 4 causes the deenergization of the signals-at-stop relay M followed by the deenergization of the lock relay L which relay L is normally energized by a circuit closed from through a circuit including front contact 16 of relay 6T, front contact ll of relay IT, front contact 18 of relay M, approach locking selections AP, windings of relay L, to The closure of the back contact 49 of the relay L completes a stick circuit for the relay WZ from the negative terminal of the field battery FB, through a circuit including polar contact 6! in a left hand position, front contact 62 of relay WZ, back contact 49 of relay L, windings of relay WZ, to the midtap of the field battery FB. This circuit maintains the relay WZ energized although it is prevented from further control from the central ofiice.

The opening of front contact 49 deenergizes the lock repeating relayLP which opens the front contact 53 stopping the intermittent illumination of the route indicator 4--3L, but closes back contact 63 to apply energy from through polar contact 64 of relay WP in a left hand position to the route indicator 4--3L so that it is steadily illuminated. This steady illumination of the route indicator on the trackway diagram advises the operator that the route has been completed and is locked.

The clearing of the signal is indicated by the illuminating of the signal indicator 48K by suitable means not shown. This has been illustrated in Fig. 2 by the shading of indicator 4SK.

With such illumination of the trackway diagram as above described, the operator is advised as to what route is being set up and when it has reached a locked condition. When the crossover is included in either an initiated route or a completed route, the operator is advised against trying to set up a route from the signal 2 to the signal 3 for example, inasmuch as there is a portion of the miniature trackway in such conflicting route which is illuminated and which he can readily see involves the crossover.

In some cases it may be unnecessary to provide a flashing indication for an initiated route to distinguish from a completed route, and in such cases can be applied directly to the heel of contact 53 or to the bu wire 15 instead of through contact 52 of flashing relay E,

As the train accepts the signal 4 and passes over the crossover, such signal is placed at stop causing'the relay M to be picked up and causing the signal indicator 48K to be unilluminated but the lock relay L is maintained deenergized by the opening first of front contcat 15 of relay BT and then the opening of front contact T! of relay IT. As soon as the signal 4 goes to stop and such condition is indicated to the operator by the unillumination of the signal indicator 48K, he can return the entrance button 4N3 to its normal position which deenergizes the route relay 43 and the switch controlling relay Z. However, the lock repeater relay LP remains deenergized because the lock relay L does not pick up and close front contact 49 until the train has passed beyond both of the track sections 6 and l. Thus, so long as the train is in such sections, the route indicator 43L is maintained illuminated advising the operator that the route is locked and that such crossover cannot be employed for other routes until the train passes beyond the track sections involved. The occupancy of these track sections 5 and I is indicated to the operator by the illumination of the track indicators GTK and TTK controlled respectively by the track relays ET and TI although such control has not been specifically shown.

As soon as the train passes beyond the section 1 and the lock relay L is energized followed by the picking up of the lock repeating relay LP, the route indicator 4-3L i unilluminated by reason of the opening of back contact 53 and because the'relay Z has previously been deenergized opening front contact 54 upon the restoration of the entrance button 4NB to its normal position.

The provision of the lock repeating relay LP in the circuit having a contact 41 which cooperates with the contact 48 of the relay WP, is for the purpose of providing whathas been conveniently :LP to be energized. This will not be explained in detail inasmuch as such features have been disclosed in various prior applications, and has been explained specifically, for example, in the above mentioned prior application of S. NfWight, Ser.

,No. 69,905, filed March 20, 1936.

It is believed that it will be readily understood by analogy to the above description, how a route can be cleared from the signal 4 to the signal 5, or in the reverse direction, or how the various other similar routes can be set up. The operation of the entrance-exit buttons accomplishes the energization of one of the route relay 45, 4-3 or 2-3 with one polarity or the other depending upon the particular route and direction in such route to be established. However, it is' believed expedient to point out in detail the control of the route indicators or lamps under such conditions.

Assuming that the route relay 4-5 is picked up to establish a route over the main tracks 6 spec-tive route relays 4-5 and 2-3 are picked either from signal 4 -to the signal 5, or in the opposite direction, then the relay Z is energized to a normal position by reason of the closure of front contact 65 which in turn causes the energization of the route lamp 4-5L by a circuit closed from through a circuit including back contact 52 of flashing relay F, bus wire 15, front contact 53 of relay LP, front contact 54 of relay Z, polar contact 55 of relay Z in a right hand position, indicator lamp 4-5L, front contact E6 of route relay 4-5, to The energization of this route lamp 4-5L illuminates the miniature track diagram through the opening provided for it in the panel from the end walls of the slot designated by the reference characters l5 and H5 in Figs. 2 and 4.

The indicator lamp 4-5L is intermittently energized under such conditions by reason of the flashing relay F but as soon as the route is established and locked, the front contact 53 of relay LP is opened and the back contact 63 is closed. This closes a circuit from through a circuit including back contact 63 of relay LP, polar contact 64 of relay WP in a right hand position, route indicator lamp 4-5L, front contact 6% of relay 4-5, to This circuit causes the route indicator 4-5L to be steadily illuminated.

It is noted that the closure of front contact 66 of route relay 4-5 opens back contact 68 removing all negative potential from the left hand terminal of the route indicator lamp 2-3L, but this route indicator lamp 2-3L may be illuminated at the same time with the route indicator 4-5L provided the route relay 2-3 is also picked up for the establishment of'a parallel route from the signal 2 to the signal 3 or in the opposite direction.

If the route relays 4-5 and 2-3 are picked up simultaneously, or if the route relay 2-3 is picked up separately, then the route indicator r-3L will also be intermittently energized by a circuit closed from through a circuit including back contact 52 of flashing relay F, bus wire 15, front contact 53 of relay LP, front contact 54 of relay Z, polar contact 55 of relay Z in a right hand position, route indicator lamp 2-311, front contact 61 of route relay 2-3, to But it is believed that under the usual circumstances these 'route relays 4-5 and 2-3 will not be simultaneously picked up although they may often be in picked up positions contemporaneously. If such is true, the operation of the crossover TS will be accomplished by the first route relay picked up with the flashing of its corresponding route lamp, while the picking up of the second route relay will immediately cause the steady illumination of the route lamp, as the crossover would already be locked with relay LP dropped away.

Upon the dropping of the lock repeating relay LP with the route relay 2-3 picked up, a circuit is closed from through a circuit including back contact 63 of relay LP, polar contact 64 of relay WP in a right hand position, route indicator lamp 2-3L, front contact 61 of route relay 2-3, to

In other words, when the crossover TS is in a reverse position and is controlled to such position by the relay Z, the route indicator 4-31. is illuminated in accordance with the condition of such crossover; but when the crossover is controlled to a normal position and is in such normal position, one or the other of the normal route indicators 4-5L or 2-3Lis illuminated depending upon whether'one or both "of the re- The manner in which the dropping of either or both of the track relays ST and IT will cause the holding of the crossover locked in a' normal position will be readily understood by analogy to the locking previously described for the reverse position. Y This locking of the crossover will cause the steady illumination of the particular route indicator selected by the route relay or relays picked up, and if all of the route relays governing traffic over the crossover TS are dropped away, then the reverse route lamp 4-3L will be illuminated with crossover TS in a reverse position or both the normal route lamps 4-5L and 2-3L will be illuminated with the crossover in a normal position. This operation is clear as the polar contact 64 of relay WP selects the normal or reverse route lamps when the lock repeating relay LP is dropped away while with both the route relays 4-5 and 2-3 dropped away both contacts 66 and 61 of these respective relays apply to the route lamps 2-3L and 4-5L respectively.

Individual control of the track switch-The operation of the emergency switch control lever ISML so as to close the contact 44 in a left hand position energizes the relay Z through its upper winding by a circuit including the back contact 45 until the polar contact 42 is operated to the right after which such polar contact allows the continued energization of the relay Z by contact 44 irrespective of the picking up of the neutral contacts of the relay. Similarly, the operation of the contact 44 to a right hand reverse position,

causes the energization of the lower windings of the relay Z through a circuit including the back contact 4| of relay Z until the polar contact 42 is operated to the left so that the relay Z continues to be energized although the neutral contacts of the relay are picked up. It is apparent however, as above pointed out, that if the emergency-switch machine control lever ISML is opdated to a position contrary to the position determined of a particular route relay already picked up, then such operation of the emergency switch control lever ISML will not cause the energization of the relay Z in the opposite direction because both neutral contacts 4| and 45 are picked up and the polar contact 42 will not allow such opposite energization.

The energization of the relay Z due to the operation of the emergency switch control lever ISML, causes the intermittent energization of the route indicator 4-3L for the reverse position or the intermittent energization of both of the normal indicators 4-5L and 2-3L for the normal position. The circuit for this will be apparent when it is pointed out that the deenergization of the route relays 4-5 and 2-3 close their respective back contacts 66 and 6'! to apply energyto the route indicator opposite to the one which it controls when such route relay is picked up. Also, if the crossover TS becomes looked under such manual control by the lever lSML, or becomes locked due to the hand signalling of a train through one or both of the track sections, then either the reverse indicator 4-3L will be illuminated or both of the normal indicators 4-51; and 2-3L will be illuminated, which illumination will be steady by reason of the closure of back contact 63 of relay LP.

It may be desirable in some cases to know the position of the track switch without causing the operation of the emergency switch control lever SML and for this purpose anemergency indication button IEB is provided which is a selfrestoring push button to apply potential to contact 64 which obviously energizes the proper indicators in accordance with the position of the switch as indicated by the switch position indicating relay WP. This self-restoring push button 1 EB may be omitted if desired. h

A correspondence indication is provided for the purpose of knowing whether or not the switch control relay Z is in correspondence with the track switch under such conditions as require the operation of ,the lever ISML. This correspondence indicator ICOR is energized. whenever the track switch TS is unlocked, as indicated by the deenergization of therelay WP, by a circuit closed from'(+), through a circuit including back contact Hi, correspondence lamp QR, c,

Whenever the relay Z is out of correspondence with the locked position of the track switch as indicated by the relay WP, a circuitis' closed for the corresponding indicator .ICOR from through front contact of relay WP, polar contact H of relay WP in a normal positiongpolar contact 12 of relay Z in a reverse position out of correspondence with relay WP, correspondence lamp ICOR, to It is apparent that if the track switch is in a reverse position with polar contact ll to the left and the polar contact 12 of relay Z is ina normal right hand position that a similar circuit is established for the indicator Icon, a 1 r r The flashing relay F maybe omittedii desired and positive potential may be applied to the bus wire 15 so that steady illumination of the indicators is provided at all times although it appears desirable to provide a flashing indication under the operation of the track switch until the route is established so as to distinguish between those routes which are being established and those which have already been established. Also, if desired, instead of using a flashing relay F, a constantly running motordriven interrupter may be employed to supply interrupted positive potential to the bus wire 15, or other control may be provided which operates onlywhen needed. In any event, it is believed that there are many equivalents of the flashing relay F which may be substituted within the scope of the present invention.

a Summary The present invention provides an illuminated trackway diagram associated with the entrance and exit buttons of an NX interlocking system in such a way as to give the position of the track switches involved without using miniature movable sswitch points. This is believed to be desirable so as to eliminate as many moving parts as possible onthe diagram. This system of controlalso gives an indication of that part of the trackway to be employed in the establishment of a particular route at the initiation of the route controLso that the operator may readily distinguish the newly proposed route from those routes which have already been established; The indications given" also provide composite routeinformation that warns the operator against andeavoringto set upa conflicting route or to disturb a route already locked due to the presence of a train although the' entrance buttons may all be track switch withoutpperating' theentrance-exit buttons or even endeavoring to set up a routeby the control of the emergency switch lever ISML.

Having thus described a centralized traific con: trolling system for railroads, as one specific embodiment of the present invention, it is to be understood that various modifications, adaptations, and alterations may be applied to meet the requirements of practice without in any manner departing from the spirit or scope of the invention except as limited by the appended claims.

What I claim is: 1

1. In an interlocking systemior railroads, a track layout made up of sections of track interconnected by track switches to form a plurality of routes with signals governing traffic at the entrances to such routes, entrance buttons for the entrances to said routes, exit buttons for the ends of said routes, means for setting up a route in response to the joint actuation of the entrance and exit buttons for that route by operating the track switches in such route and clearing its signal, a miniature track diagram corresponding to said track layout, means for indicating the route or routes to be set up in response to the joint actuation of said entrance and exit buttons for a route or routes by intermittently illuminating substantially throughout their length the' portions of the miniature track diagram corresponding to such route or routes, and means for indi cating the route or routes actually set up by steadily illuminating the same'portions of the miniature track diagram corresponding to such route or routes. 7 2. In an interlocking system for railroads, a track layout made up of sections of track interconnected by track switches to form a plurality of routes with signals governingtrairic at the entrances to such routes, means for setting up each'route by operating the track switches in such route and clearing its respective signal, .a miniature track diagram corresponding to said track layout and provided with route portions identifying the different positions of the track switcheswhich portions may beselectively illuminated, and manually operable means for illuminating those of said route portions corresponding to the operated positions of said track switches, said manually-operable means acting independently of said means for setting up each route and independently of the occupied or unoccupiedcondition of the corresponding route.

in their normal positions; A furtherfeaturef is provided in that the operator may under e'mer: gency conditions "ascertain fthe'position' of the 3. In an interlocking system for railroads, a track switch, a switch machine for operating said track switch, a double winding differentially wound neutral-polar relay for controlling the operation of said switch machine, signals for governing trafiic over'said track switch, manually operable entrance and exit buttons associated with the entrance and exit ends of each route over said track switch, a route relay for each route over said track switch energized by the joint actuation of the entrance and exit buttons for that route for controlling both said neutral-polar relay and said signals, circuit-means for energizing one winding of said neutral-polar relay controlled by one. route relay when said track switch is required to be in one position for the route corresponding to'thatone route relay, other circuit means for energizing the other winding of said neutral-polar relay controlled by anotherlroute relay whensaid track switch is required to be in its other position for the route corresponding to said another route relay, back c ntacts on said neutral-polar relayior allowing said circuit means and said other circuit means to be initially effective only when said neutralpolar relay is deenergized, and polar contacts on said neutral-polar relay allowing said circuit means and said other circuit means to be con- I tinuously effective for only one position of said polar-neutral relay while such neutral-polar relay is energized.

4. In an interlocking system for railroads, a track switch, a switch machine for operating said track switch, a double winding differentially wound neutral-polar relay for controlling the operation of said switch machine, signals for governing traific over said track switch, manually operable entrance and exit buttons associated with the entrance and exit ends of each route over said track switch, a route relay for each route over said track switch energized by the joint actuation of the entrance and exit buttons for that route for controlling both said neutral-polar relay and said signals, circuit means for energizing one winding of said neutral-polar relay controlled by one route relay when said track switch is required to be in one position for the route corresponding to that one route relay,

other circuit means for energizing the other winding of said neutral-polar relay controlled by another route relay'when said track switch is required to be in its other position for the route corresponding to said another route relay, a manually operable lever, auxiliary circuit means controlled by said manually operable lever to energize one or the other windings of said neutralpolar relay in accordance with the position of said manually operable lever independently of said route relays, back contacts on said neutralpolar relay allowing said circuit means and said other circuit means controlled by said route relays as well as said auxiliary circuit means controlled by said manually operable lever to be initially efifective only when said neutral-polar relay is deenergized, and polar contacts on said neutral-polar relay allowing said circuit means and said other circuit means governed by said route relays as well as said auxiliary circuit means controlled by said manually operable lever to be continuously effective for only one position of said neutral-polar relay While such neutralpolar relay is energized.

5. In combination, a control panel having a track layout represented thereonas including two track sections connected by a track switch, a normal indicator for illuminating one of said represented track sections, a reverse indicator for illuminating the other of said represented track sections,xentrance and exit buttons on said control panel for ends of said track sections, route establishing means effective upon the operation of only an entrance button for one end of a track section and an exit button for the opposite end of such track section for causing the normal or reverse operation of said track switch in the actual track layout as required to set up a route over that track section, and means controlled by said route establishing means for intermittently energizing said normal or said reverse indicator to provide a flashing illumination indicating the position to which said track switch is being controlled by said route establishing means.

6. In combination, a control panel having a track layout represented thereon as including two track section's connected by a track switch and having signals for governing trafiic thereover, normal and reverse indicators for illuminating linear portions of said represented track .layou't identifying the normal and reverse positions of said track switch, manually operable control means on said control panel for causing the normal and reverse operation of said track switch in the actual track layout and for clearing one of said signals,- circuit means governed by said manually operable control meansfor energizing said normal or reverse indicator when said manually operable control means is causing a corresponding normal or reverse operation of said track switch, and means for rendering said circuit means ineiiective and for energizing said normal or reverse indicator dependent upon the actual position of said track switch in the actual track layout whenever one of said signals is cleared.

7. In a system for controlling the power operation of track switches of a railway track layout, a control panel having thereon a miniature track diagram of the track layout and including normal'and reverse indicators for illuminating linearportions of represented track corresponding to the normal and reverse positions of a track switch, manually operable control means for causing the normal and reverse operation of said track switch, means governed by said manually operable control means for energizing said normal or reverse indicator when said manually operable control means is causing a corresponding normal or reverse operation of said track switch, and means for energizing said normal or reverse indicator depending upon the position of said track switch and acting independently of said manually operable control means whenever said one or said other track section is occupied by a train.

8. In a system for controlling the power operation of track switches of a railway track layout, a control panel having thereon a miniature track diagram of the track layout and including normal and reverse indicators for illuminating linear portions of represented track corresponding to the normal and reverse positions of a track switch, manually operable control means for governing the normal and reverse operation of said track switch in said track layout, means controlled by said manually operable control means for energizing said normal or reverse indicator when said manually operable control means is governing a corresponding normal or reverse operation of said track switch, and other manually governable means for energizing said normal or reverse indicator depending upon the position of said track switch and acting independently of said manually operable control means.

9. In combination, a track layout including two track sections connected by a track switch and having signals for governing traiiic thereover, a control panel having said track layout represented thereon by having distinctive portions for said two track sections, a first indicator for illuminating one of said portions, a second indicater for illuminating the other of said portions, said indicators illuminating the corresponding portions substantially throughout their length, entrance and'exit buttons on said control panel for the ends of said track sections, route estab 'lishing means efiective upon the joint operation of only an entrance button for one end of a track section and an exit button for the opposite end of such track section for causing the normal or reverse operation or said track switch and the clearing of the proper signal to set up a selected route .over that track: section, and circuit means track diagram of the track layout and including 3 normal and reverse indicators for illuminating linear portions of represented track corresponding to the normal and reverse positions of a track switch, entrance and exit buttons on said control panel for the ends of said track sectionsmeans effective upon the operation of an entrance button for one end of a track section and an exit button for the opposite end of such track section for causing the normal or reverse operation of said track switch in the track layout as required!v to set up a route over that track section, means controlled by said entrance and exit buttons for energizing said normal or said reverse indicator when a route is set up over said one or said other track section, and'other means acting to distinctively energize said first or second indicators when the corresponding track section is occupied by a train.

11. In combination, a track layout including two track sections connected by a track switch,

a control panel having said track layout represented thereon by two miniature track sections connected by a track switch; a normal indicator for illuminating one of said miniature track sections, a reverse indicator for illuminating theother of said miniature track sections, manually operable control means for causing the normal and reverse operation of said track switch, means governed bylsaid manually operable control means for selectively energizing said normal or reverse indicator when said manually operable control means is causing a corresponding normal or reverse operation of said track switch,

and means for distinctively energizing said normal or reverse indicator to give a different indicar.

tion depending upon the position of said track switch when a route has been set up over such track switch in response to said manually operable control means.

12. In combination; a panel having a track layout represented thereon by strips of translucent material for each stretch of trackway, certain of said strips of material being interconnected in a manner indicative of track switches;

means for at times intermittently illuminating se- 1 lected ones of said strips of material to display a particular proposed route among the several routes through the track layout; and means changing an intermittent illumination to a steady illumination when the track switches are in proper positions and said particular route is actually set up.

. 13. In an interlocking system for railroads, a track layout made up of sections of track interconnected by track switches to form a plurality of routes with signals governing traific at the entrances to such routes, entrance buttons for the entrances to said routes, exit buttons for the ends of said routes, route establishing means for setting up a route in response to the joint actuation of only the entrance and exit buttons for that route by operating the track switches in such route and clearing its signal, aminiature track diagram having miniature track portions corresponding to said track sections of said track layout, and means for indicating each route set up by illuminating substantially throughout their length those portions of the miniature track diagram corresponding to the track sections actually included in that route, said means being controlled in part by said route establishing means and in part by the traiiic conditions in said track sections to provide an illuminated outlinelof a route when it is established or is occupiedlby a train.

14. In combination; a track layout having track sections connected by track switches with signals for governing trafiic thereover; a panel having said track layout represented thereon by portions of miniature trackway for each of said track sections, certain of said portions being interconnected in a manner indicative of said track switches; manually operable control means on said panel for the ends of said sections; route establishing means responsive to said manually operable control means for the opposite ends of a section to operate the track switches to set up a route over said section and clear a signal therefor; means for illuminating in one way the miniature trackway portion corresponding to the track section over which said route establishing means is setting up a route; and means for distinctively and differently illuminating the same miniature trackway portion corresponding to the track section over which a route is actually set up and has its signal therefor cleared; whereby a proposed route is clearly distinguishable from a route actually set up.

15. In an interlocking system for railroads; a track layout including sections of track interconnected by track switches to form a plurality of routes with signals for governing trafiic thereover; a control panel having said track layout represented thereon by portions of miniature trackway corresponding to said track sections, certain of said portions being interconnected in a manner indicative of track switches; manually operable control means on said control panel for the ends of said routes; route establishing means responsive to the actuation of said manually operable control means for the opposite ends of a particular route to thereby operate the track switches to set up that route over its track sections and clear a signal therefor; means controlled by said route establishing means for illuminating the miniature trackway portions corresponding to the trackway sections over which said particular route is established, whereby the operator is advised of an "established route by a strip of illuminated miniature trackway so that when there are no routes set up the control panel is normally dark; and means associated with the track and switches manually operable independently of said manually operable control means for causing the selective illumination of the miniature track portions adjacent a track switch in accordance with its then operated position without clearing a signal, whereby an operator can ascertain the position of a track switch by the illumination of the track diagram without actuating said manually operable control means for the ends of said routes.v

16. A track layout including two portions of track connected by a track switch, a control panel having thereon a representation in miniature of said track portions and said connecting track switch, normal and reverse indicators comprising substantially linear strips of translucent material in the portions of track represented on said track diagram and corresponding with the normal and reverse positions of said switch, manually operable buttons on said control 'panel for the ends of said track portions, route establishing :means effective upon the operation of a button for the entrance end of a track portion and a button for the opposite exit end of that track portion for causing the normal or reverse operation of said track switch in the track layout as required to set up a route, and means controlled by said route establishing means in response to the operation of said buttons and dependent upon the operated position of said track switch for illuminating said normal or said reverse indicator when a route has been set up over the track switch in the corresponding positicn and for also illuminating said indicator independently of said route establishing means while said route is occupied by a train.

1'7. A switch and signal control system for railroad track layouts having a plurality of poweroperated switch points movable to different positions to provide various routes for train movement from one signal location to another, certain of said routes beingconfiicting and others non-conflicting comprising, in combination with a control panel having thereon a miniature track diagram of the track layout, manually operable buttons located on said track diagram adjacent the signal locations represented thereon, route establishing means including a plurality of route circuits each individually belonging to a corresponding one of the desired routes through said track layout, said route establishing means being responsive to the joint operation of the two buttons alone belonging to the signal locations at the ends of any given desired route to energize the corresponding route circuit, means responsive to the energization of any given route circuit for preventing the energization of the route circuits for all other conflicting routes, switch and signal control means responsive to the energization of a given route circuit for positioning the switch points for that route and for also controlling the clearing of a signal for train movement over that route, indicating means associated with said track diagram for illuminating linear portions of the track represented thereon of substantial length adjacent the switch points, and means responsive to the energization of a given route circuit and dependent upon the operated position of the switch points for controlling said indicating means to outline the corresponding route by illuminating a substantial part of the track on said track diagram to show the position of the switch in that route, and other indicators on i said track diagram lighted While a train is present.

18. In a switch and signal control system for railroad track layouts having a plurality 01" power-operated switch points movable to provide a plurality of routes between signal locations,

certain of said routes being conflicting, a control panel having thereon a miniature track diagram of the track layout, manually operable buttons on said diagram adjacent the signal locations represented thereon, switch control means energizable to normal or reverse conditions for governing the operation of said switch points to corresponding normal or reverse positions, a plurality of route circuits one for each of said routes and energized by the joint operation of the buttons alone for the signal locations at the ends of the corresponding route, each of said route circuits acting to condition the switch con- .trol means of the switch points in thatroute for operation to the normal or reverse position as required for that route, means responsive to the energization of a given route circuit for preventing the energization of the route circuits for all conflicting routes, indicating means on said track diagram for illuminating substantially linear portions of the track involved in the various routes, l hting c rcu ts f r said indica n means, and means responsive to the energization of a route circuit when said buttons are operated for a proposed route and Operating independently of the operated position of the switch points for closing the lighting circuit of a selected indicating means to illuminate on said track diagram the portion .of track included in that proposed route, said'lighting circuits including contacts closed dependent on the normal or reverse condition of the corresponding switch control means.

'19. A switch and signal control system for railroad track layouts having power-operated switch points movable to provide various routes through said track layout between signal locations comprising, a control panel having thereon ,a miniature track diagram of the track layout and manually operable buttons adjacent the signal locations, route establishing means including a plurality of route circuits one belonging to each of the desired routes through said track layout and energized by the joint operation of the two buttons alone for the signal locations at the ends of the corresponding route, switch control relay means responsive to the energization of said route circuits and assuming normal or reverse controlconditions upon energization of a given route circuit .to position the switch points in the corresponding route to the normal or reverse position as required, means responsive to theenergization of algiven route circuit for preventing .the energization of the route circuits .fOr all conflicting routes, indicating means associated with said track diagram for illuminating substantially linear portions of the track involved in the various routes, means responsive to the .energization of aogiven route circuit and operating independently of the operated position of the corresponding switch points for illuminating a portion of track included in the corresponding proposed route, and means responsive to the presence of a train .in a route and operating independently of the condition of said route circuits for maintaining such portion of track illuminated while said train is present.

20. In combination with a railway track switch, .a control lever having an inactive position and a normal and a reverse control position,

normally inactive means .for indicating the condition of the switch, switch control means controlled by said lever, means for actuating said switch control means tooperate the track switch :to normal or reverse'in response to the movement o'f-saidleverto its normal or reversecontrol position, :means for-energizing said indicating means in response to the movement .of said "lever to either control position, and means for distinctively energizing said indicating means independently of the condition of said lever to indicate when the switch is out of correspondence with said switch control means.

21. In an interlocking control system, ;a plu-.

rality of iroutesthrough a track layout each ,including -.a track switch, a control panel comprising a representation of said track layout having a route button forreach routeend, a route selector controlled by therbuttons atopposite ends of 'is moved to either control position to light one of said indication lamps.

22. In a switch and signal control system of the entrance-exit type for governing the power operation of track switches of a railway track layout to provide routes for train movement comprising, a control panel having thereon a miniature track diagram of the track layout, control buttons on said control panel for designating entrance and exit ends of desired routes, normal and reverse switch position indicating means including lamps for illuminating substantially linear portions of said track diagram corresponding with the normal and reverse positions of each switch, route establishing means responsive to the manual operation of buttons to designate entrance and exit ends of a desired route for operating the switches as required to establish that route and for lighting lamps of said indicating means for corresponding positions of said switches, an auxiliary switch control lever for each switch having a normally inactive position and movable to a normal or reverse control position to operate said switch independently of the manual operation of said buttons, and means effective whenever an auxiliary switch control lever is operated to a control position for lighting one of said indicating means for the corresponding switch even though said control lever is moved to a different position from the existing position of said switch, thereby indicating on said track diagram when an auxiliary switch control 3 lever has been operated from its normal inactive position.

23. In a system of the entrance-exit type for governing the power operation of switches of a track layout providing different routes, a miniature track diagram of said track layout having portions of track representative of the difierent track switches and track sections of the track layout, control buttons on the track diagram for the ends of the different routes afiorded by the track layout, indicator means associated with the different track switches and adapted to illuminate portions of the track diagram adjacent the represented switches to indicate the positions of such switches, switch control means for governing the power operation of each of the track switches to normal or reverse positions, route establishing circuit means responsive to the manual actuation of the control buttons for the opposite ends of any given route for energizing ;the switch control means associated with the switches in that route to cause the operation of such switches to the proper normal or reverse, positions, the energization of the switch control means for that particular route also effecting the illumination of the indication means to indicate the positions of such switches required to establish that route, an auxiliary switch control lever associated with each switch and provided with an inactive position together with normal and reverse control positions, circuit means associated with each auxiliary switch control lever lnormally inactive when such lever is in .an in- 5 active position and' rendered active when such lever is in normal or reverse control positions for energizing the associated switch control means for causing the normal or reverse operation of the associated track switch, the energization of such switch control means at the same time efiecting the illumination of the indicator means associated with that track switch for indicating the position to which that switch is being controlled.

24. In a system of the entrance-exit type for governing the power operation of switches of a track layout providing different routes, a miniature track diagram of said track layout having portions of track representative of the difierent track switches and track sections of the track layout, control buttons on the track diagram for the ends of the different routes aiiorded by the track layout, indicator means associated with the different track switches and adapted to illuminate portions of the track diagram adjacent the represented switches to indicate the positions of such switches, switch control means for governing the power operation of each of the track switches to normal or reverse positions, route establishing circuit means responsive to the manual actuation of the control buttons for the opposite ends of any given route for energizing the switch control means associated with the switches in that route to cause the operation of such switches to the proper normal or reverse positions, the energization of the switch control means for that particular route also effecting the illumination of the indication means to indicate the positions of such switches required to establish that route, an auxiliary switch control lever associated with each switch and provided with an inactive position together with normal and reverse control positions, circuit means associated with each auxiliary control lever being normally inactive when such lever is in an inactive position and rendered active when such lever is in normal or reverse control positions for energizing the associated switch control means for causing the normalor reverse operation of the associated track switch, the energization of such switch control means at the same time effecting the illumination of the indicator means associated with that track switch for indicating the position to which that switch is being controlled, and in- :dicator means associated with each track switch and controlled by its switch control means so as to indicate when that track switch is in correspondence with its switch control means.

25. In a switch and signal control system of the entrance-exit type, a control panel having thereon a miniature track diagram of the track layout under the control .of the operator, route control means including manually operable buttons associated with said track diagram for governing the power operation of switches and clearing of a signal for any route in response to the actuation of buttons to designate the entrance and exit ends of that route, indicating means associated with each portion of said track diagram relating to the different positions of said switches and adapted to illuminate substantially linear portions of said track diagram, circuit means responsive'to the operation of said route control means to initiate switch operation for a route for rendering eiTective said indicating means for all portions of said track diagram included in said route independently of the operated position of the switches and thereby outline the route to be established by a substantially continuous line of light throughout its length, and means including normally extinguished correspondence lamps for visually indicating when each switch is operated into a position to correspond with the control thereof exercised by said route control means.

26. A control panel for switch and signal control systems of the entrance-exit type comprising, a miniature track diagram of the track layout under the control of the operator, manually operable buttons mounted adjacent points of said track diagram representing signal locations constituting the entrance and exit ends of routes, route establishing means responsive to the operation of buttons to designate entrance and exit ends of routes for governing the power operation of switches and clearing of signals for said routes, indicating means including a lamp for illuminating a substantially linear portion of track diagram for each position of each switch, a flasher device for intermittently opening and closing a circuit, and circuit means responsive to the operation of said route establishing means to initiate operation of switches to set up a route for connecting said flasher device to thelamps of the indicating means associated with the position of each switch included in said route until the route has been established,

27. In a system of the entrance-exit type for governing the power operation of track switches to interconnect the track sections of a track layout to provide different routes between signal locations constituting entrance and exit points, a track relay for each track section, a track dia gram of said track layout having miniature portions of track representative of the different track switches and track sections of the track layout, control buttons on the track diagram at points corresponding to the signal locations and operable to designate the corresponding signal locations as entrance or exit ends of the different routes afforded by the track layout, indicating means associated with each of the miniature track portions of said track diagram relating to parts of different routes and adapted to illuminate said miniature track portion substantially throughout its length, route control means responsive to operation of buttons to designate the entrance and exit ends of a route for operating the track switches to establish that route and for controlling said indicating means to illuminate th track portions of said track diagram representing that route, means for maintaining said track portions illuminated independently of said route control means when a train is in said route, and an indicating lamp associated with each of said track portions and efiective when the corresponding track relay is de'energized to give a distinctive aspect to the corresponding indicating means and show that said track portion is occupied by a train.

28. In a system of the entrance-exit type for governing the switches and signals of a track layout providing different routes between signal locations constituting entrance and exit points, a miniature track diagram of said track layout having portions representative of the diiferent track switches and track sections of the track layout, control buttons on the track diagram at g points corresponding to the signal locations constituting the entrance and exit ends of the various routes, indicating means for illuminating substantially linear portions of said track diagram relating to the different routes, route control means responsive to the manual actuation of the buttons to designate the entrance and exit ends of any given route for operating track switches to establish that route and for controlling said indicating means to illuminate the track portions of said track diagram relating to said route, an indicating lamp for each of said track portions adapted when lighted to give a distinctive illuminated appearance of the corresponding miniatur track portion, and track circuit controlled means for lighting each of said indicating lamps when the corresponding track section is occupied by a train.

29. In an interlocking system for railroads, a track layout made up of sections of track interconnected by track switches to form a plurality of routes with signals governing traffic at the entrances to such routes, manually controlled route establishing means for setting up each route by operating the track switches in such route and clearing its respective signal, a miniature track diagram having substantially linear route portions corresponding to the sections of said track layout which route portions may be selectively illuminated, and means for selectively illuminating those of said route portions identifying a route actually set up by said route establishing means, said means also acting to maintain such illumination of such route portions for that route so long as it is occupied by a train independently of the manual restoration of said route establishing means.

30. In an entrance-exit type interlocking system for railroads, a track layout made up of sections of track interconnected by track switches to form a plurality of routes with signals governing trafiic at the entrances to such routes, route establishing means for setting up each route by operating the track switches in such route and clearing its respective signal in response to manual actuation designating the entrance and exit ends of that route, a miniature track diagram corresponding to said track layout and made up of substantially linear route portions which may be selectively illuminated, and means for selectively illuminating those of said route portions corresponding to a route actually set up by said route establishing means or occupied by a train, said means acting independently of the manual restoration of said route establishing means, whereby an operator .is warned against endeavoring to: set up a route conflicting with a route already set up or occupied.

31. In a switch control system for railroads, a control panel having thereon a miniature track diagram of a track layout and including a normal indicator and a reverse indicator for illuminating linear portions of the represented track adjacent a switch to identify the position of that switch, manually operable control means on said control panel for causing the normal and reverse operation of said track switch in the actual track layout, and means for intermittently energizing said normal or said reverse indicator when said manually operable means is causing a corresponding normal or reverse operation of said track switch, and for steadily energizing the same indicator when the track switch has operated to the controlled position.

FOREST B. HITCHCOCK. 

